Assembly of Caenorhabditis elegans female meiotic spindles requires both MEI-1 and MEI-2 subunits of the microtubule-severing ATPase katanin. Strong loss-of-function mutants assemble apolar intersecting microtubule arrays, whereas weaker mutants assemble bipolar meiotic spindles that are longer than wild type. To determine whether katanin is also required for spindle maintenance, we monitored m...

Female germ cell meiotic divisions are typically asymmetric, giving rise to two daughter cells with different sizes. Spindle movements including spindle migration from the oocyte center to the cortex and spindle rotation from parallel to perpendicular (typically in the mouse) at the cortex are crucial for these asymmetric divisions and therefore are crucial for gamete production. Different regu...

In mitosis, a spindle checkpoint plays important roles at the metaphase-anaphase transition to ensure the formation of a bipolar spindle, the completion of connecting chromosomes to microtubules and the alignment of all chromosomes at the spindle equator before initiation of anaphase. Components of the spindle checkpoint were first identified through genetic screens in budding yeast and some ch...

In meiosis I, exchanges provide a connection between homologous chromosome pairs that facilitates their proper attachment to the meiotic spindle. In many eukaryotes, homologous chromosomes that fail to become linked by exchanges exhibit elevated levels of meiotic errors, but they do not segregate randomly, demonstrating that mechanisms beyond exchange can promote proper meiosis I segregation. T...

BACKGROUND The clinical efficacy of the current methods used for cryopreservation of metaphase II human oocytes is low. Meiotic spindle disorders are thought to be largely responsible for this situation. METHODS Supernumerary fresh metaphase II human oocytes were cryopreserved in 1,2-propanediol with 0.1 M sucrose using a slow freezing/rapid thawing programme. Meiotic spindles were analysed i...

Meiotic chromosome segregation leads to the production of haploid germ cells. During meiosis I (MI) the paired homologous chromosomes are separated. Meiosis II (MII) segregation leads to the separation of paired sister chromatids. In the budding yeast, Saccharomyces cerevisiae, both of these divisions take place in a single nucleus, giving rise to the four spored ascus. We have modeled the micr...

In the present study, we discovered that mouse oocyte maturation was inhibited by simulated microgravity via disturbing spindle organization. We cultured mouse oocytes under microgravity condition simulated by NASA's rotary cell culture system, examined the maturation rate and observed the spindle morphology (organization of cytoskeleton) during the mouse oocytes meiotic maturation. While the r...

Oocytes segregate chromosomes in the absence of centrosomes. In this situation, the chromosomes direct spindle assembly. It is still unclear in this system which factors are required for homologous chromosome bi-orientation and spindle assembly. The Drosophila kinesin-6 protein Subito, although nonessential for mitotic spindle assembly, is required to organize a bipolar meiotic spindle and chro...

Mitotic spindles assemble from two centrosomes, which are major microtubule-organizing centers (MTOCs) that contain centrioles. Meiotic spindles in oocytes, however, lack centrioles. In mouse oocytes, spindle microtubules are nucleated from multiple acentriolar MTOCs that are sorted and clustered prior to completion of spindle assembly in an "inside-out" mechanism, ending with establishment of ...

Axin-1, a negative regulator of Wnt signaling, is a versatile scaffold protein involved in centrosome separation and spindle assembly in mitosis, but its function in mammalian oogenesis remains unknown. Here we examined the localization and function of Axin-1 during meiotic maturation in mouse oocytes. Immunofluorescence analysis showed that Axin-1 was localized around the spindle. Knockdown of...